Δ8-Tetrahydrocannabinoquinone (HU-336) is a potent anti-angiogenic agent that inhibits angiogenesis by directly inducing apoptosis in vascular endothelial cells. It achieves this without altering the expression of pro-angiogenic and anti-angiogenic cytokines and receptors. Δ8-Tetrahydrocannabinoquinone also shows significant effectiveness against tumor xenografts in nude mice.